Clayco Inc., the development firm founded in St. Louis by Bob Clark in 1984, is moving its headquarters to Chicago.

Chicago is, after all, where Clark has lived since 2010, when he moved there after his wife died. “It’s a formality,” Clark said in an interview with the Business Journal Thursday. “This is where I live, and headquarters is where the chairman and CEO lives.”

Chicago Mayor Rahm Emanuel is making the announcement today, and in a statement said, “Clayco is exactly the kind of company were are looking to attract.”

St. Louis will remain integral to the business, Clark said, and none of Clayco’s approximately 700 employees here will be laid off. The company will have about 280 employees in Chicago, a number it expects to double over the next couple of years. “We will continue to grow in St. Louis, as well,” he said.

Clayco, with annual revenue of more than $820 million, will occupy the 13th and 27th floor of the Jewelers Building in the heart of the Loop. The company recently signed a 15-year lease in St. Louis at 2199 Innerbelt Business Center Drive and invested $1 million.

St. Louis will remain the home of Clayco’s Concrete Strategies division and its Forum Studio architectural practice. The company’s accounting and IT operations also will stay in St. Louis.

As for Chicago, Clark said, “It’s a terrific place to live, as is St. Louis,” and he said he has embraced his move. “It was a change of scenery and a challenge for me. It’s been uplifting for me and for everyone in the company.”

In a press release, Clark added, “Chicago is simply the best location for the company given our growing national and international design and engineering business,” and the city’s two airports, Midway and O’Hare. “In addition, for a growing company like ours to be in a world class city attracting the best and brightest young minds in our industry matches with our goals and objectives.”

Clayco’s national clients include Dow Chemical Co., Amazon, Caterpillar, Proctor and Gamble, 3M and Chevron. In St. Louis, it is working on projects for the new downtown Saint Louis University law school, Missouri Baptist Hospital, BJC HealthCare and Washington University. Chicago area clients include Kraft Foods, Blue Cross Blue Shield and the University of Illinois.

Clayco is not seeking or receiving any subsidies as part of the headquarters relocation.